The invention relates to thermoplastic blends having improved properties. Optionally, these blends may be dynamically vulcanized.
Significant research has been conducted in an effort to find polymer blends which have a combination of both elastic and thermoplastic properties. These polymer blends have been given the generic designation of Thermoplastic Olefins (xe2x80x9cTPOxe2x80x9d). They exhibit some of the properties of a cured elastomer as well as the reprocessability of thermoplastic resins. The elastomeric characteristics may be enhanced if one component of the blend is a vulcanizable elastomer which is wholly or partially cross-linked.
The earliest work in the curing of TPO compositions was by Gessler and Haslett; see U.S. Pat. No. 3,037,954. That patent teaches the concept of xe2x80x9cdynamic curingxe2x80x9d wherein a vulcanizable elastomer is dispersed into a resinous thermoplastic polymer and the elastomer cured while continuously mixing and shearing the polymer blend. The result is a micro-gel dispersion of cured rubber in an uncured matrix of resinous thermoplastic polymer. Gessler""s U.S. Pat. No. 3,037,954 discloses compositions comprising polypropylene and a rubber wherein the rubber may be butyl rubber, chlorinated butyl rubber, polybutadiene, polychloroprene and polyisobutene. Compositions of about 50 to 95 parts polypropylene and about 5 to 50 parts of rubber are disclosed.
Dynamically vulcanized thermoplastic compositions comprising a polyamide and various types of elastomers are known. See, for example, U.S. Pat. Nos. 4,173,556; 4,197,379; 4,207,404; 4,297,453; 4,338,413; 4,348,502; and 4,419,499.
It has now been found that compositions comprising a thermoplastic resin and chloromethylated(styrene-isobutylene)copolymer have improved properties which make them particularly useful in the manufacture of tires. The compositions may also comprise uncured or dynamically cured elastomers.
This invention is directed generally to a composition comprising a blend of chloromethylated(styrene-isobutylene)copolymer and a thermoplastic resin selected from the group consisting of polyamides, polyesters, polycarbonates, polysulfones, polyacetals, polyacetones, acrylonitrile-butadiene styrene resins, polyphenylene oxide, polyphenylene sulfide, styrene-acrylonitrile resins, styrene-maleic anhydride resins, polyamides, aromatic polyketones, ethylene vinyl alcohol copolymer and mixtures thereof Tires and tire components such as air permeation prevention films comprising these compositions are also provided.